The stabilization of the shale and sandstone cliff along Colorado Highway 3 south of Durango will extend into December.

An earlier estimate that the work would end Nov. 18 was too optimistic, Nancy Shanks, Colorado Department of Transportation communications manager in Durango, said Tuesday.

The contractor, TK Construction, was slowed by wet weather and an unexpected extension of a project in Wyoming, which reduced the size of the crew in Durango, Shanks said.

Shanks said they expected to finish by Nov. 18.

“But the contract allows them to have Highway 3 closed until Dec. 19,” she said.

Work is proceeding full-bore now, as workers install protective netting. Previously, crews removed 5,000 cubic yards of rock and debris, fixed bolts to stabilize the 0.7-mile cliff and installed more than 400 anchors to support the netting.

Whether work extends until the December date isn’t certain, Shanks said.

The Highway 3 work is at least the second time in recent years that CDOT has contracted for rock removal there. Rocks tumbling from the cliff have struck vehicles.

The lower portion of the cliff is Lewis Shale, topped by pictured-cliffs sandstone. A fruitland coal deposit lies immediately behind the ridge.

The contract for Highway 3 work also includes rockfall mitigation on Colorado Highway 145 south of Telluride, Shanks said.

The total cost is $1.56 million.

daler@durangoherald.com